This invention relates to a control valve that controls the pressure or volume of a fluid, and more particularly to a single-seat globe control valve.
According to their design, the control valves can be classified as globe, angle, butterfly, ball, sluice or other types. Because of its rigid structure and good controlling characteristics, the globe type is most widely used. Globe control valves fall into two broad classifications, depending on the number of seat it contains: (1) the double-seat type; and (2) the single-seat type.
The double-seat globe control valves have an advantage in that their stems can be driven with a remarkably small amount of force. However, this type of valve cannot achieve a perfectly tight closure because it has to close two seats at a time. This results in considerable leakage even while the valve is closed. Due to its high susceptibility to erosion and cavitation, the body and other parts rapidly wear out or break down thus causing annoying noises.
As opposed to the double-seat type, the conventional single-seat globe control valves have good shut-off and dynamic characteristics. However, they require a considerably large amount of force to drive their stems.
This invention has solved the aforementioned problems with the conventional control valves.